New BACnet Standard Published with Significant Improvements to Alarm Handling

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Atlanta — Changes to the newly published BACnet standard from ASHRAE will encourage smart lighting controls and other building automation controls systems.

ANSI/ASHRAE Standard 135-2012, BACnet – A Data Communication Protocol for Building Automation and Control Networks, allows building equipment and systems manufactured by different companies to work together. It is the only open, consensus-developed standard in the building controls industry.

The new standard is being published ahead of schedule due to the wide-reaching changes in alarming functionality made by addendum af to Standard 135-2010. This edition of the standard also includes recently adopted changes for the lighting industry.

Addendum af provides significant improvements to the alarm handling in BACnet including: improved fault handling, temporary alarm recipient subscriptions, improvements in scalability of alarm distribution and simplifications in alarm distribution to support less complex products, according to Carl Neilson, chair of the Standard 135 committee.

“For building owners/integrators these changes allow improvements in interoperability between lighting control products and other building automation systems,” he said. “Hopefully, this facilitates more deployment and integration of smart lighting controls, such as lights that turn on/off when occupants enter/leave rooms; lights that come on based on the same schedules as climate control; and opportunities to reduce lighting based on energy usage during demand/response events. With the changes in alarming, we also hope to see alarming support in ‘smaller’ devices, which should provide more alarm and fault detection with a lower engineering cost.”

Addendum af contains 32 parts. Changes include:
• Removal of Annex C and Annex D
• Clarification of optionality of properties related to intrinsic event reporting; optionality of properties related to change of value reporting; priority_array and relinquish_default; segmentation related properties; virtual terminal related properties; time synchronization interval properties,  backup and restore properties; active_COV_subscriptions property; slave proxy properties; restart related properties; log_deviceobjectproperty; clock aligning properties; and occupancy counting properties are allowed to be present
• Ensures that pulse_rate and limit_monitoring_interval are always together and that that event notifications are not ignored due to character set issues
• Adds the ability to configure event message text; event detection enable/disable property; dynamically suppress event detection; specify a different time delay for to-normal transitions; inhibit the evaluation of fault conditions; for some objects types to send only fault notifications; a notification forwarder object type; an alert enrollment object type
• Separates the detection of fault conditions from intrinsic reporting
• Makes the event reporting property descriptions consistent
• Identifies the property in each object that is monitored by intrinsic reporting
• Changes the description of the reliability property
• Improves fault detection in event enrollment objects and the specification of event reporting
• Reduces the requirements on notification-servers

This version of the standard also includes the addition of support for lighting control through the new lighting output object, the channel object and the WriteGroup service.

The cost of ANSI/ASHRAE Standard 135-2012, BACnet—A Data Communication Protocol for Building Automation and Control Networks, is $170 ($140, ASHRAE members).

To order, contact ASHRAE Customer Contact Center at 1-800-527-4723 (United States and Canada) or 404-636-8400 (worldwide), fax 678-539-2129, or visit

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